No idea about AMD but I have nvidia 3070 and works just fine. I use gnome for gaming and kde works well too. No settings changed, simple archinstall script with nvidia proprietary drivers and steam.
I'm not sure why but xfce multi screen gaming is problematic, haven't dived into it.
Not saying don't get AMD but nvidia has horrible reputation which is kinda unfair nowadays. Their driver has improved a lot.
I'm sorry for late reply didn't get the notification. Does Xorg struggle with multi monitor gaming? I use awesomewm on top of xfce and don't want to abandon it. If that's the case it sucks. Any ideas?